The Pentax K-3 is a 24-megapixel Pentax high-end digital single-lens reflex camera with an APS-C sensor, announced on 7 October 2013. The Pentax K-3 is the successor to both the K-5 II and K-5 IIs models, which have a 16-megapixel sensor. The K-5 II had an optical low pass filter or anti-aliasing (AA) filter that can prevent the appearance of moire patterning on the captured image. This filter reduces the sharpness of the image, so Pentax also produced the K-5 IIs which omitted this filter. In the K-3, Pentax obviated the need for providing two separate models by including a selectable AA filter "simulator". This mechanism vibrates the sensor when switched on, slightly blurring the image in a way that replaces the function of the optical AA filter, providing the same benefit as the filter in the K-5 II and other cameras with an optical AA filter. When the AA simulator is disabled, the sensor records a sharper image, as in the K-5 IIs.